Computed Tomography by Ms. Nouf Alzahrani Dr. Saddiq Jastniah King Abdulaziz University Faculty of...
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Computed Tomography by Ms. Nouf Alzahrani Dr. Saddiq Jastniah King Abdulaziz University Faculty of Applied Medical Science Radiology Department- 2 nd year
Computed Tomography by Ms. Nouf Alzahrani Dr. Saddiq Jastniah
King Abdulaziz University Faculty of Applied Medical Science
Radiology Department- 2 nd year
Slide 2
What is a computed tomography Scan It is a non-invasive medical
imaging procedure that combines the use of X-rays and computer
processing to generate tomographic (slices) of the area scanned. A
computerized axial tomography scan is more commonly known by its
abbreviated name, CAT scan or CT scan Four classifications of the
types of scans: Abdominal-Bone-Head-Vascular
Slide 3
CT scanner
Slide 4
System components of CT scanner scanner room operating room
computer room CT unit is divided into three main rooms:
GANTRY This is shaped like a giant donut and it maintains the
alignment of the x ray tube and detectors
Slide 7
: Gantry Houses ( components) from inside : X ray tube :
produce the x rays (ionizing radiation) with continuous exposure.
Filter: to reduce the low energy x rays which are not useful for
imaging Collimators: Pre patient collimator mounted on the tube
housing, creates more parallel beam and reduce patient dose. Post
patient collimator reduces the scatter radiation on the detector.
Detector arrays: to absorb the x ray beam and located at the
opposite side of the tube. X ray tube Detector arrays
Slide 8
Filter preC Patient postC Detector DAS
Slide 9
components from out side : Display panel. Control panel.
Emergency button. Aperture
Slide 10
DescriptionFunctionIcon When pressed, stops X-ray exposure,
turns off the laser alignment lights, halts all gantry and table
motions. Stop Scan Scan Start When pressed, the table moves in,
toward the.Gantry Table In When pressed, the cradle moves out, away
from the gantry. Table Out When pressed, the table moves up and
towards the gantry. When the table moves up with the laser
alignment lights on, the cradle will adjust horizontally to
maintain the anatomic reference point Table Up Control panel
Slide 11
A toggle when pressed, turns all the laser alignment lights on
or off. These are used to help establish landmark locations. Laser
Alignment Light Pressing (Cradle Lock) once unlocks the table,
making it "free floating". This means that the cradle can be moved
freely with your hands. Table Lock/Release DescriptionFunctionIcon
When pressed, the table moves down and away from the gantry. Table
Down When pressed in conjunction with Table Up/Down or Cradle
In/Out, causes those functions to operate at a faster speed. Fast
Speed Pressing allows you to view the current gantry tilt range and
scannable range, based on table position, on the gantry display
panel. Tilt and Table Travel Limits Pressing (Home) simultaneously
moves the cradle out of the gantry and return the gantry tilt to
zero degrees.. Home Control panel
Slide 12
Gantry Display The gantry display provides gantry and table
status information
Slide 13
The CT table may be either flat or curved and it is used to
load a patient for scanning. It is usually made of carbon fiber
material that is strong enough; the table must be capable of
vertical (up down) and horizontal (in out) movements.
Slide 14
Automatic injector Some examinations require injection of
contrast media to highlight specific areas. The injector is used to
inject the contrast through vessels automatically and it consists
of: 1 Two syringes: one for contrast, and the other for saline
"water". 2 Connecting tube. 3 Cannula (needle) with appropriate
size. 4 Injector control monitor and it is located in the operating
console room.
Slide 15
Accessories 15 head holder Axial head holder Coronal head
holder U shaped Foam insert Cradle extender Knee cushion Arm
support Foam wedges
Slide 16
The operating console will usually have tow TV monitors: 1 Scan
monitor: this monitor can be mainly used for scanning patients,
adjusting the technical factors, slice thickness, angle of gantry
and initiates scan, record patient data(hospital identification,
name, patient number, age,sex ) and to provide identification for
each scan. 2 Display monitor: used to view the resulting images to
manipulate post scan data, post processing workmeasurement and 3D
formations before sending to the radiologists. 3
Keyboard/mouse
Slide 17
Scan monitor The Scan monitor contains the user interface that
controls all aspects of scanning from entering patient information
to ending the patient exam.
Slide 18
1. Emergency Stop - In the event of an emergency situation,
pressing emergency stops, stops all table and gantry motions. 2.
Exposure Indicator - The (Exposure Indicator) illuminate amber when
an actual exposure is taking place. 3. Start Scan - The (Start
Scan) indicator flashes green once the tube has reached exposure
speed. Simply press the button to start the scan. Start Scan will
flash for 30 seconds before timing out. 1. Emergency Stop - In the
event of an emergency situation, pressing emergency stops, stops
all table and gantry motions. 2. Exposure Indicator - The (Exposure
Indicator) illuminate amber when an actual exposure is taking
place. 3. Start Scan - The (Start Scan) indicator flashes green
once the tube has reached exposure speed. Simply press the button
to start the scan. Start Scan will flash for 30 seconds before
timing out.. Keyboard and Scan Interface module 2 13 475 7 6
Slide 19
5 4. Move to Scan - The (Move to Scan) indicator flashes green
indicating that the system is ready for you to advance the cradle
into the starting position. Simply press the button to advance the
cradle. Move to Scan will flash for 180 seconds before timing out.
Remote Tilt (Prescribed Tilt)- 5. Remote Tilt (Prescribed Tilt)-
Press (Prescribed Tilt) and hold the button down until the
prescribe tilt is achieved. Talk - 6. Talk - Pressing (Talk) and
speaking towards the intercom above the button allows you to
communicate with the scan room. Volume Control (operator to
patient) 7. Volume Control (operator to patient) - This dial
controls the volume of the operators voice to the patient.
Slide 20
Slide 21
Use this procedure each time you start a new patient exam. It
is best to setup the patient information before you get the patient
on the table. 1.click Patient Schedule, 2. From the scan monitor,
click [New Patient]. 3. click {add patient} The Patient Information
screen appears automatically displaying the new Exam Number. Enter
the patient information. Click [Accept] to save changes and add
patient information to the schedule list. Set Up Patient
Information
Slide 22
1.From the scan monitor, click [New Patient]. 2. Then Set
Patient Information 22
Slide 23
Position the Patient 23 1.Head first 2.Feet first
Slide 24
Selecting a Protocol 1. On the left monitor, place the mouse
over the area that you want to scan and click on it. A list of all
the protocols that you built in this area of the protocol manager
appears. 2. From the list, select the protocol that you want to use
by clicking on it. Brain routine
Slide 25
Slide 26
Image 26 Scout View Axial Image
Slide 27
Slide 28
What happens when x-ray passes through the patient? Attenuated
and measured by the detector X ray tube and detectors are hidden
inside the gantry of scanner and rotate around patient during
scanning Detector converts x ray photons into electrical signals
(analog), which must be converted into digital (numerical) for
input on computer Computer makes the image reconstruction process
Reconstructing an image is in numerical form and must be converted
into electrical signal so it can be displayed on a television
monitor for viewing Image can be stored on magnetic tapes or
optical disks and recorded on x-ray film
Slide 29
CT images
Slide 30
Manipulation transverse axial images can be reformatted into
coronal, sagittal, and three dimensional processing
Slide 31
Computer room The computer is designed to solve many equations
through controlling data acquisition, processing, displaying, and
storage.
Slide 32
Scanners store image data on either floppy disk or magnetic
tapes. HARD COPY LASER PRINTERS